The present invention relates to a tubular packaging casing, suitable for use as a sausage casing having a seam extending along its longitudinal axis. The packaging comprises a tubing formed from a flat film of cellulose hydrate, preferably fiber-reinforced cellulose hydrate, having a plasticizer content of from about 5 to 20% by weight, relative to the weight of the casing. The two edges of the flat film, which are formed into the tubing, are joined by means of a sewing thread.
The present invention additionally relates to a flat film for producing the packaging casing.
A tubular packaging casing of this type, as well as the flat film used to form the casing, are known. The use of the tubular casing as a sausage casing is also known. However, in the known casing, the material to be packaged is stuffed manually.
These packaging casings and flat films have the disadvantage that they are not very well suited for use in automatic, high-speed stuffing and clipping devices intended for tubular casings without a seam. As is known, these devices employ relatively high stuffing pressures. As a result thereof, the seam zone of the packaging casing is subjected to much higher strain than in the case of manual stuffing. Therefore, a high tear resistance of the casing material in the area of the holes made by the needle is required.
After automatic stuffing with sausage meat, it has been observed that a sewn sausage casing comprising fiber-reinforced cellulose hydrate, with a customary moisture content of, for example, up to 10% by weight and a glycerol content of 5 to 15% by weight, relative to the weight of the casing, usually exhibits three tears, mutually offset by an angle of about 120.degree., in the area around the puncture holes made by the needle. These tears, which start from the center of each puncture hole, extend in an outward direction.
The sewn packaging casings used to date exhibit still further disadvantages during stuffing. The diameters of the puncture holes formed by the needle during sewing are necessarily larger than the diameter of the sewing thread. As a consequence thereof, areas of free space are obtained in the packaging casing between the thread and the periphery of the puncture holes.